Below knee tissues

Mak et al [4] (Table B4.2) measured the in-vivo indentation properties of the below knee tissues of young adults (N=6) between the ages of 25 and 35. A 4 mm diameter indentor was used, with a final indentation of about 5 mm. The fixed indentation was then maintained for 2-3 seconds to observe the difference between initial and relaxed (equilibrium) properties. The tests were done with the knee in 20° of flexion and were repeated with and without muscular contraction. The Poisson s ratio was assumed to be 0.5 for initial measurements and 0.45 for relaxed (equilibrium) measurements. 

The authors investigated the bulk tissue behaviour of the below-knee amputee s residual limb. An assessment of Young s modulus was made by matching the indentation experimental curves with the curves produced by the finite element modelling of the indentation into a layer of tissue with idealized mechanical properties. In vivo tests, conducted at four sites of a below-knee amputee s limb (patella tendon, popliteal, and anterolateral regions) found the local moduli to be 145, 50, 50 and 120 kPa respectively. The effect of muscle tension on the measured indentation response was also investigated. The results showed that the stiffness increased with muscle contraction. 

His surgeons offered little hope. He had gangrene, a rotting of tissue due to lack of oxygen, and the surgeons said an amputation of the left leg below the knee was necessary. If he refused the surgery, they would have to operate later and take off the entire leg—fix it now, or pay more later. 

The "central" deposition of fat in patients, such as Corti Solemia, with Cushing s "disease" or syndrome is not readily explained because GCs actually cause lipolysis in adipose tissue. The increased appetite caused by an excess of GC and the lipogenic effects of the hyperinsulinemia that accompanies the GC-induced chronic increase in blood glucose levels have been suggested as possible causes. Why the fat is deposited centrally under these circumstances, however, is not understood. This central deposition leads to the development of a large fat pad at the center of the upper back ("buffalo hump"), to accumulation of fat in the cheeks and jowls ("moon facies") and neck area, as well as a marked increase in abdominal fat. Simultaneously, there is a loss of adipose and muscle tissue below the elbows and knees, exaggerating the appearance of "central obesity" in Cushing s "disease" or syndrome. 

The following discussion is useful in designing a template for tissue repair and regeneration applications. By way of an example, the design parameters listed below are specifically applied to the development of a resorbable collagen based template for guiding meniscal tissue repair and regeneration in the knee joint. 

Interventions for limb salvage are required if a patient develops rest pain, nonhealing ulcers, or gangrene of the toes or foot. After appropriate treatment, rest pain disappears, ulcers heal with standard attention, and gangrenous tissue can be amputated with prompt healing. This allows substitution of a minor toe or forefoot amputation for an otherwise inevitable below- or above-knee amputation. All effort is made to preserve as much extremity as possible so that the potential for rehabilitation is optimal. 

In general, knee intra-articular effusion of less than 6-8 ml cannot he appreciated clinically. Below this threshold, lateral X-ray projections are able to demonstrate intra-articular fluid by demonstrating the fat pad separation sign , which consists of the presence of a soft-tissue opacity >5 mm between the suprapatellar fat and the prefemoral fat (Fig. 14.115). This sign has been reported positive even for effu-... 

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